it's not a very good score.....
The Midyis score is standardized, so 100 is average. Somewhere around 116 would be one standard deviation about average, so that suggests 120 is just above the cusp to be "above average". However, that is just observed score and there is a huge margin of error in such assessments as trying to measuring attainment in the brain is complex. So in reality, what the child actually knows will be somewhere between 108-132 midyis score. From the midyis score alone, it does seem reasonable to ensure that student is prepared to go through university.
MidYIS (Middle Years Information System) assesses a student's cognitive abilities, including verbal reasoning, non-verbal reasoning, and mathematical reasoning. It aims to provide insights into a student's potential academic performance and identify areas where they may need additional support or challenge.
Hi! An average MidYIS score is 100 so 154 is an extremely good standard. If your child keeps up the effort in achieving their obviously high potential they should be well on their way to A/A* s in GCSE and A-Level. It's highly likely that your child will be accepted into Oxford University if their obvious talent is nurtured and nourished throughout their school years. They are likely to be in the top 1% of the population so maybe MENSA would be an option?
Apparently the mean score is 100, and the standard deviation is 15. This means that 67% of the population will score between 85 and 115. Higher scores are better. The company selling the midyis system will give, as well as scores, predictions of what the child should be able to achieve at GCSE level. Schools can then use this to a) track a child's progress compared with their theoretical capability predicted by the test, and b) to see if they have "added value" by raising the child to achieve more (or less) than predicted.
Some studies suggest that a little extra stimulation in class could help boost performance. For example, taking notes on colored paper has been proven to improve handwriting of children. If the child is distracted because of being bored, talk to a teacher about giving more challenge (not just more) assignments to him or her or giving them homework early to figure out as an individual.